ᐅ Adjustment of the Ventilation System – Special Case

Hello, I hope you can help me with the following question.
We live in a detached single-family house built in 2018, meeting the KFW 55 standard, with walls made of filled brick. The house has a volume of almost 1000 cm3 (61 cubic inches).
We have a Wolf CWL 400 ventilation system. At the moment, only two of us live here (children are planned). We both work full time and leave the house at 7:00 AM and return around 6:00 PM on weekdays. Now we are wondering what the required air exchange rate should be and how to best set the ventilation system so that we need as little heating as possible in winter while still having clean air.

At night, the system runs at 130 m3 per hour (4600 cubic feet per hour), and during the day at 250 m3 per hour (8800 cubic feet per hour).
Basically, we want the bathroom and bedroom to be ventilated adequately. After showering, we ventilate the bathroom briefly anyway, but then wet towels still dry there.
Otherwise, we spend a short time in the kitchen and living room in the morning for breakfast and about three hours in the evening. In my opinion, the ventilation is set too high for this situation.

It looks different on weekends. There, we cook extensively, have guests, do laundry, etc. Therefore, I would leave everything as it is on Saturdays and Sundays, but for the weekdays I would like to hear your opinion.

Hello,
Just give it a try—run the system at 130 m³/h (4600 ft³/h) and see what happens.
But don’t expect too much: the system likely has a heat exchanger for heat recovery from the exhaust air. The efficiency is high, so its impact on heating costs is usually negligible.

In our house (640 m³ (22,600 ft³) with 4 occupants), the system runs continuously at about 170 m³/h (6000 ft³/h), with an increased flow of 250 m³/h (8800 ft³/h) for 3 hours in the morning. This works very well; we always have fresh air inside.

In general:
130 m³/h (4600 ft³/h) at night seems quite low to me, meaning not much air will reach the bedroom. The purpose of the system should be that the air quality in the morning upon waking is as good as it was the night before when going to sleep.

Best regards,

Andreas

You can get hygrometers from Xiaomi made in China for next to nothing. In theory, they could even track the data in an app.

And why? The humidity level of the air is not the original poster’s problem.

@BBaumeister

Just lower the system a bit in the morning. In general, it helps to try different settings back and forth until you find the “right” values for your situation.

Where do you see a special case now? In my opinion, this is a completely normal use case.

More useful than a hygrometer would be to install the air quality sensors from Wolf, which then automatically adjust the system up or down as needed.

You are overthinking it. Just run it on nominal ventilation. That usually works fine.

If it really is 1000 cubic meters (35,315 cubic feet) – a huge building – your system will generally be significantly undersized and not properly designed.

I think there is a calculation error here. That would be roughly 350 m² (3750 sq ft).

The idea isn’t entirely wrong. I had similar thoughts after moving in. But of course, you could also just set everything to nominal ventilation and forget about it.